Assessment on variation of performance indicators under phosphorus-starved conditions in a core-set of rice cultivars and their diversity in pup1-linked DNA marker-haplotypes

The development of phosphorous deficiency tolerance (PDT) in rice cultivars is important for sustainable rice production. If the performances (PDT indicators) of the rice cultivars can be correlated with Pup1 (major QTL linked to PDT in rice) haplotypes, marker assisted breeding (MAB) programmes could be launched to produce phosphorous deficiency tolerant rice varieties. In the present study, 27 rice cultivars (nine landraces and 18 improved varieties) were screened under P-deficient soil conditions in two seasons, Yala and Maha, the major cropping seasons in Sri Lanka, based on shoot dry weight, and P utilisation efficiency. To establish the basis for MAB of PDT, the Pup1 haplotypes were assessed using 17 Pup1 linked DNA markers and sequence polymorphism of the two marker loci, K29 and RM28102. The PDT screening results revealed that the performance of the rice cultivars is seasonal dependent. The landrace Madathawalu and the old-improved variety H-4 showed highest trait values for yield, shoot dry weight, and P utilisation efficiency in both Yala and Maha seasons. Remarkably, Madathawalu and H-4 share a common Pup1 haplotype demonstrating that MAB for phosphorous deficiency tolerant rice cultivars is possible using these two rice cultivars as parents. The Pup1 linked marker haplotypes and variation of the PDT indicators of the studied cultivars can be used to conduct MAB programmes to develop improved rice varieties.